In a water pump used for cooling an internal combustion engine (engine), a rotating shaft is supported to a body via a bearing. A drive pulley is fixed to one end of the rotating shaft and an impeller is fixedly attached to the other end of the same. Between the impeller and the bearing, a mechanical seal is disposed for preventing leak of cooling water through a gap of the rotating shaft. However, with such water pump, it is difficult to stop completely leak of cooling water via the mechanical seal. For this reason, there is known an arrangement in which the body of the pump is provided with a drain passage for discharging leaked cooling water to the outside of the pump. However, cooling water leaked from the drain passage forms water marks on the surfaces of the body and other component, which adversely affect the component or which can be erroneously determined as a defect of the water pump.
As a measure to cope with such inconvenience as above, in the case of a water pump of PTL 1, the body is provided with a discharge opening communicated to a space formed between the mechanical seal and the bearing and a reservoir communicated to the lower side of this discharge opening. With this arrangement, cooling water that has leaked from the mechanical seal can be reserved in the reservoir, thus preventing leakage of cooling water to the outside of the body.
Further, in the case of a water pump of PTL 2, the body is provided with a drain hole for draining cooling water that has leaked into the seal chamber of the bearing and a water-absorbing member (a felt, etc.) is provided downstream the drain hole, so that cooling water leaking from the mechanical seal is reserved within the water-absorbing member.